Apparatus for determining the depth of liquid in tanks



Aug. 151950 J. N. MATTHEWS APPARATUS FOR DETERMINING THE DEPTH 0F LIQUID IN TANKS Filed Jan. 18. 1946 2 Sheets-Sheet 1 INVENTOR; 715mm Fin-l me? A Aug. 15, 1950 J. N. MATTHEWS 2,518, 8

APPARATUS FDR DETERMINING THE DEPTH 0N LIQUID IN TA KS Filed Jan. 18, 1946 2 Sheets-Sheet 2 Patented Aug. 15, 1950 TE srArsls PATENT OFFICE APPARATUS'FORDETERMININGTHE DEPT -OFLIQUID IN TANKS Joseph N. :Matthewaliakewood, Ohio Application Januar 18, 1946, Serial No. 641,899

(01. =,'zs .s02)

This invention relates to apparatus for ascer- "taining the depth "or liquidselectively in a series of tanks, more'particul'arlythe ballast tanks f or water on 'ships,where-by the "ships draft may' loe .iregu'la'ted or changed by the commanding officer 1 to meet "operating conditions, that is, where lu) the ship is being propelled without -a load, fully loaded or partially loaded and/ or --(b) the ships load 'isfinot properlydistributed and/or the Zbody of water, 'through'which "the ship is being i ,propelledfis 'calm-o'r'in varying degrees-of roughness. Likewise, the ship must *be "trimmed to avoid engagemeritwith equipment on 'wharves or piers when "tyingthereto or "being shifted therealong. To insure efficientgpropulsi'on under'these v conditions it is;necessary'to"ascertain the-depthor the .water inteac'h tank or certain of the tan-ks, s0 as to determine which tanksshould be supj ,plie'd with additional water, the volumetherein or other tanks reduced, or all of :the waterin the tanks withdrawn therefrom. Other "ennuitions arise Where'itishiglily'importantt'o quickly ,Ide'termine the depth of rwaterin the tanks-cerltaintanks .or an thereof for "example, when all or substantiallyall '0fth'e water is to be with- (drawn,.in which'event thepumps must beslowed fdown int'ime toprevent the'latter 'from pump- Tingair, instead oftwateniromthetanks. Each ship, ,wihen, designed has a certain "cargo carry- Tingeapacity and,a certain capacityfor ballast, ,thellatter to be increased or decreased'ia's condi "tionsreguire byv supplying water to nne or more ---Qf. thB ballasttanks or discharging water there Lfrom. "Once the ballast .tariksarefilled, "thereyquired ballast regulation ,andZor draft of the shiplto meet the qperating'honditi'ons above re- Iferred'to atiany time can .be determined "by meas suring the hydrostatic head in 'one or'moreof the fMy invention "has beenxapplied to'arship or ,'boat of the ore carrying type. On ships of this type, so far aSLmy' knowledgego'es, it"is us :tomeiryfor aseaman to standon'th'e ships deck andgnrojeclt, a 'rodfirito thenvater 'ineach tank (or 'inone or more ftanks ..according to his orders) to measure the, depth of the'water'th'erein bythe "waterline on theiod, Aside fromthe fact'tha-t these operations involve an -undue amount of labor andtime, it is often a dangerous physical :matelywfiflo :feetdong and containaas "many as .18 tanks (9 tanks at each side of the shipihohis). .Myzinventiomeliminates the disadvantages ieabove referred to .on the cone -l1and :and on theother :hand provides for readily taking static-head readings in all of the tanks, or selectivelwas-rdesired, at a :central station, inra short :period of time, whereby the trim of the ship may be quickly :regulated :or phanged.

One object *of =-the invention :is to providejmproved apparatus for determining at a single ,operatingor central station on aship or :hoat, the depth of -waterin any tone'or more ofcthe ballast tanks provided therein.

Another object of .the invention is toeprovide an improved apparatus Lfor .a boat whereinj'the hydrostatic-head of a column :or the :water in each tank is utilized .to determinelthe volume or quantityof wateriin'the tank, whereby the fdraft ofltherboat fore, mid-.shiporaft may'b.e.changed.

,Another object of the invention is toprovide anlimprovedapparatus 'arrangedto utilize a fluid in -a gaseous .phase supplied under pressure "to Qdisplace :a column of watertin a tank, whereby the applied pressure serves to indicateth'e "depth *of water in the tarik.

,Another object of the invention 'is to provide ,an improvedapparatus ior ascertaining the depth .of liquid in ya, tank-or like container, wherein pneumatic pressure is utilizedto determine the ,static-head of the liquid, the applied pressure. as

- ls'hownlon agage, serving toindicaterthedepth moi liquid .in ,the tank.

Another object of the invention "is to "provide an improved apparatus "wherein, by means "of a master valve pneumatic pressure "maybe "se- .flectively applied to liquid 'in a "Series "of tanks todmeasure the static-head of the liquid therein, the applied pressure to each "tank being shown by agage graduated to" indicate the depthof the liquid-in the tank. I

A "further objectof the invention is "to provide an improved apparatus of simple construction for readily determining the depth of water" in' the tanks on a boat, whereby thedraft o'f the boat fore, aft and mid-ship "may be regulated -dependent on whether the boat is l'oaded'or" empty and/or existing water "and weather conditions.

Another "objectof the invention is to provide an improved apparatus operable"to-determine'selectively the depth of liquid in a series o'f -tanks and automatically indicate --'the depth for each tank at the operating station or location and simultaneously ata remote station or location.

Another object of the invention is to provide an improved process of determining the depth of liquid in each of the ballast tanks of a ship, whereby the draft thereof may be changed in relation to the ships load dependent on the weather and other conditions.

Another object of the invention is to provide in an improved apparatus for determining the depth of the" water in the ballast tanks of a ship by the application of air under pressure, means for determining the resistance to the flow of the air to the tanks under varying atmospheric and/or barometrical conditions, whereby accuracy in determining the water depth in each tank results.

A further object ofthe invention is to provide an improved multi-way valve of simple construction.

Other objects of the invention will be apparent to those skilled in the art to which my invention relates from the following description taken in connection with the accompanyin drawings, "wherein:

Fig 1 is a view, partly in side elevation and partly in section on the line l-| of Fig. 2, of a boat equipped with apparatus embodying my invention, I

' Fig. 21s a section on the line 2-2 of Fig.

enlarged.

.Fig. 3 is a longitudinal section through the valve, substantially on the line 3-3 of Fig. 4.

Fig. 4 is a plan view of the valve. Fig. 5 is a diagrammatic view, the valve being in section on the line 5-5 of Fig. 3.

. Fig. 6 is a diagrammatic view showing the system for indicating the depth of the water in the respective tanks at a remote location.

Fig. 7 is an elevation view of a suitable manometer for use with the device. I

In the drawings, A indicates as an entirety a boat of the ore carrying type, which is chosen to exemplify the application of my invention, constructed to provide (41) holds B between the bow and. super-structure (pilot house and oflicers quarters) (land the stern D containing the engine room d and (b) tanks along the port and starboard sides of the boat, at either side of the holds B, the tanks on they port side being desigated I, 2, 3, 4, 5 and 6 and those on the starboard side being designated I, 2', 3, 4, 5' and, It. will be understood. that. the number of tanks on each side of the boat A will depend on its length and other factors. Each tank is provided for by the outer side wall a of the hull, the

side and bottom walls I) of the adjacent ,hold B,

the bottom wall a of the hull, a partition b" on the reinforcing plates g between the bottom walls a and 2), these pipes being connected to one or more pumps (not shown) the operation of which serves to supply water therethrough to the tanks and draw water therefrom in maintaining or changing the trim of the boat. In the application of the invention above referred to the top walls of the tanks were approximately 23 /2feet above the hull bottom wall a and when filled to the usual level the water depth was approxi- 4 mately 22 feet, so as to leave a space above the water level in the tanks.

I indicates a pipe depending vertically into each tank and terminating a short distance (preferably approximately three inches) above the bottom wall a. The lower or free end of each pipe I is open, so that the water in the adjacent tank rises and falls in the pipe corresponding to that in the tank incident to the supply of water to the tank or withdrawal of water therefrom. The upper end of each pipe I is connected to one end of a pipe 'I'a, preferably leading through the adjacent space E and connected at its opposite end to a port 8 formed in the casing 8a of a master valve 9, which is located at an operating station, such as the engine room (1. As will be understood from Fig. 5, the valve casing 8a is formed with a plurality of ports 8, corresponding to the number of tanks, each pipe la being connected to one of these ports. By preference, as shown in Fig. 1, intermediate portions of the pipes Ia (except the pipes related to tanks 6 and 6) between the tanks and valve 9 are extended upwardly, as shown at I, to permit gravitation of condensation of moisture in the pipes. In this arrangement condensation in one portion of each pipe la drains back into the adjacent pipe I and condensation in the other portion drains into a collector lb, preferably consisting of a U-section (one only being shown) interposed in the pipe 10 in close relation to and at a level below the valve 9. The bottom portion of the U-section lb is provided with a discharge opening which is sealed closed by a screw plug.

The inner wall of the valve casing 8a is of conical shape to form a seat for the valve element l'l! having at one side a device (preferably a wheel) 10a for turning it and at its opposite end a shank Mb. The outer end portion of the shank lab is provided with screw threads to take a nut H. The nut H serves as an abutment for the outer end of a spring I la coiled around the shank lflb; the inner end of the spring Ha engages an annular plate l2 seated on the valve casing 811. In this arrangement the spring Ha cooperates with the nut l l' and plate 12 to yieldably maintain the valve element It) in its seat in the casing Ba. The side wall of the valve element I0 is formed with an annular recess l3 which registers with the inner end of an inletport l3a formed in the valve casing 8a. The outer end of the port |3a is connected to a conduit M, to which a fluid in the gaseous phase (preferably air) under pressure is supplied from a reservoir Ma. At one side of the recess I'3, the valve element is formed with a duct l5 having a vertical portion connected with the recess l3 and an outwardly extending portion arranged to register with each of the ports 8, whereby by rotation of the valve element I0, air under pressure is supplied from the conduit 14 to each of the ports 8 according to the angular position of the valve element. As the valve element ID is provided with only one duct l5, all of the ports 8 are closed when the valve element is in neutral position (see Fig. 5) and when the valve element is rotated to connect the duct IS with any one of the ports 8 all of the remaining ports are closed. The air under pressure may be supplied to the reservoir [4a. from any suitable source; that is, a compressor on board the boat and forming part of its equipment and connected to the reservoir l4a or from a suitable pump l1 connected to the reservoir and driven by a suitable motor Ila (the pump and motor being shown tanks are empty? due to"'frictiono- *is preferably maintained at fapprcacnmaitely 2. pounds fpressure; Ea'ch' pi-pe 1a rproxfiided ad jacent the Valve 9 withe cut-"eff lm, adapted to' be nlosed when "repairs are needed and 93159 eet in ladjusted positiom'when tests or "readings are .Jnadegas 'laterset forth, to eetemme the back 1 pressure or resistance *tofiair #flevv in each =ef the pipes *Ta (including each pipe 1, ii ballast T the air flowing itherethrongh. "1-8 indicates a -=s1fita2ble gage "iconnected to the conduit I 4 "for registering the pressure when areading fol-each tank made,

either with 'respectto *theresistance to airtfidw able adjustable constant :pressur. "valve interposed in {the conduit "M between the airweservdir Illa and .the g ge "I 8. '20 "indicates adjustable "walve in "the pipe 14 between the valve "1 9' and ftheigagefi. The alve 19 {is preferably set to supply air to the :conduit i-4 "atapproziimately I0 .poundspressuraWhereasihe 'valve iu is adljusteld to permit the flow of approfiimattly 2 1 cubic "feet of air per minute through the con- The .valve 2!! "is "adjustable "to provide sufficient air flowto each ;pipe Twhenair pressure .communication is established' therewith to enable a quick .readingiinfeach operation of "the valve 19. 20a, indicates 'aasafety valve connected to the conduit F4 and adapted to relieve excess pressure-th'erein, "that is, pressure above the limit providedforby "the'ga'ge F8, to avoid-*d-amageto the latter. "21"indicatesa'suitable safety valve ""rnountew'on "the *top wall "o'lthe r'eservoir Ma. l 4b indicates a cut-off prov-ided in the conduit 'I I 4 adjacent "the valve 9 "to -c1ose the'la)ti;er when fit "is ""found' necessary "to inspect or "repair the fiyalve rother rpartswof the eystem.

j plAsWill be "understood, the-pipe 1 in each bal- Gila-st tank provides a column -01? water substanjially equal in depth'to that in' the a "acent tank "at all times (except-as "hereinafter set iorth) ,'-s0 that by displacing the -wa ter =in= the pipe the "application thereto of air unGer pressm e, the pressure, which is required for such displacement, as indicated on the gage, will "equa'l the "static-'head'of the volume *dfwa'ter in tl' xe pipe 'and this pressure in turn, in connectionwwith i the-computations later referred to, isuti1ized to indicate the depth of thewaiier 'in the tank. Ac-

the depth of the waiterin the' pipe measured i=in 'Teet' and inches.

'Thegage I Bs'howni-n Fig. 515m theagraduated dial typegbutother forms of gages may be sem- U -ployed, sueh asa manometer-shown in r77.

, In operation of my apparatus' th'e firs'tfistep is to -'determine the back pressure due to frictional resistance of the pipes 1a to the iflow hilt/11812111 therethrough and 120' set "the yalyes In: in soperatfing' pcsi'tion, s0 that by thesupplymf the air pres- ":s'fire to the pipes 1 thedep'th cf' Waileriinfllhe tanks may be accurately determined. step is-carried out under the conditionsval-ready referred to "(that'is,'w ith all of thettanksiemptyor "with the-boat on -an even' l eel::arrd theetafiks fille'd to the same level :by'iflnstsopening all-of P -?theve 1ves la: and'operating the valve i9 teicenfijlithe water -1therein :.=is eliminated. It will these-be nect the=condult fil'l 'ito 'iiiheqiiipe 1a :nelated tnmne mane tanks (Bl Apr :1") rmest remcte :from lith wail ve S'Kthe waives for "the ixiipes i111 'leadingtto the 'tanlrs I, lfigheihgifiullyrcpent "andincting the *back' pressure:as-shownsby'the gage lllrin lineal '*dimen'sions. Dhe waive i9 :is then aepenated-ito 'connect "the -:conduit M with 588.1311. ithe 323110 fi and' wito li', respectiyelx,;:andleach valye rlated thereto .iis thenaadiusted :so :that the shack i310 pressure resistance ior the adjacent i-pipe "la was shown by the gage l-ll 'nilinealdimensionsisaequal to the back pressure 'first mated #with :nesnect sto the remote t'ank. -By mne'ference each valve 51a: *is then settled against l tampening hy $3, :zseetinn ixa of wire "and'a suitable "lead sslug :(not zshml-m).

"with the vailves "l w adjusted position, the sappara'tus conditioned for depth ings'k'frem time to time, which step :or aonenaition consists in operating' the walve l9 imtahlish 1.20; communication f-rem the *air supply {conduit =44 through the pipe' -lu to the pipe ll :for reach or selectively certai-ri oftheetanks dependent-sin t-he' shifis "load and/or ithe prevailing twfea ther -c'onditions, suchas' h'ereinbefore referred the.

-the hand ii for the gage l'8 *i evdlves tmelaztiye tits 1 "zero position iasishown in Fig.i 5:) in 'eachmpm- -"tion' of the 'valve *9 toconnectzthe conduits with one of the pipes la, (a the-:abomemdted lineal measurements must he-deducted irom the total lineal measurement 'ind icated on the gage l8 and (6-) to this difference or zremainder must be added a lineal dimension equall the aspecfing oi thelower-end of the adjacent .pipe 1 strain the Fbottom *a the tank toccrrectly determine 235 the depth of waterin'the adjacent tank; :this

last referred to dimension being -three iinchessaccording to "the present -disclosure. However, where "the operating -conditions under which ithe boat *is being propelled make it 'unnecessaey ito :detennme the exact water depth in ane or mrere -ta'nks, the "dimensional deduction andaddition above referred to are 'not'ma'de Wvith respect to "thedepthindicatedby"the'gage F8. Efachmpenaftion serves ('a') to displace the water i-n the wipe "1 of each tank :of' which a 'depthreading is made,

.thepressurereqiiired :forsuch di'splacemenfihe- 'ingind'ica'ted on the ge *l 8, which "being graduated'in fee'tandinches, exhibitsthe depth of the watenin each pipe "1 and enables' the-commandingioificer to determine the "depth 0f the water air :-under pressure, whereby subseguentreatlings are quickly efiec'ted. In making each -reading, lthearmo-f thegage i8 revolves aboiitiits 'axis and comes Ito .a .stop, when all of the ."water in the adjacent pi e?! is displaced, which'positiomof r .sto ppage indicates the static-head or fii'splace- :ment pressure. It wlllbe tibserved that'when the 'Qperating device 11m is in neutral position xtseerliligslAland 5),, the .val-vej .cuts .offithe supply -;Qf (air itoqall of the pipeslm; also, when "the valve 0:; element issnota'ted to .connect ;thecondu'itl 4 with each pipe la, the .supplytofceairto all of the .retmaining {pipes 1a .is cut off. .Acconding1Y,,..i1-,jfollows that, ina-displacing the water in .eachpipe 7, the ;pipes in and (the pipes I connected .Lthereto, respectively-Ame :charged -with-:air ,under ,presi sure, so that in operating the yalveifi stoi'make .-a:subsequent readingtof xthe waterdepth inieach spipe the-time 'reqnired rfor the-supplied air :presz'su'ne itc sfiOW etc the adjacent-pipe J and displace seen that the valve 9 may be readily rotated from If prior to a subsequent reading of a tank water has been supplied thereto, the static-head re-; 'sulting from such supply will cause a rise of the Water in the'adjacent pipe I and compression of the air therein; and upon making the sub- "sequent reading the supplied air pressure, in addition to the pressure in the pipe previously utilized,

to displac'ethe water therein, will be indicated on thegage by movement of the gage arm toa higher point or graduation. If prior to a subsequent depth reading of a pipe a portion of the water in the adjacent tank has been withdrawn;

therefrom, the reduced static-head in the. tank will permit escape-of air from the adjacent pipe 'I- to equalize its pressure and the 'then existing static-head, but upon making the subsequent reading theapplied air pressure corresponding tq. lthe static-head of the water in the pipe will be indicated bythe gage I8.

'lx" indicates a supplemental cut-off provided in each pipe Ia in close relation to the adjacent tank, whereby air flow to the latter may be cut off when the tank is to be inspected or its walls repaired, to avoid closing and re-setting of the adjacent valve 1.1:.

Means, indicated as an entirety at 22, are provided for simultaneously indicating at a control station-(for example-the pilot house), remote from the operating station, the reading for each tank each time a depth reading is made. The

'means 22 herein shown is of the electrical type and consists of the following: 23 indicates a casing mounted on the wall of the engine room.

'The casing encloses an are shaped resistance 23a one end of which is connected to a lead 23b, the lead in turn being connected to the positive side of a suitable battery 24, having its negative side grounded at 26a. The walls of the casing "23 support a shaft carrying an arm 25 arranged to engage the resistance 23a and movable from end to end thereof. The shaft for the arm 25 has fixed toit a gear 25a engaged by a ratchet 25b,

.. the lower end of which is provided with a piston ZE reciprocatabIe in a cylinder 26a. As shown in Fig. 5, the cylinder 23a is connected to the conduit I l, so that when the valve 9 is operated to 'measure the depth of the water in each of the pipes I the pressure operates the gage I8 and simultaneously forces the piston 28 upwardly, whereby the arm 25 is revolved relativeto the re- :sistance 23a. A spring 21 is interposed between the end wall of the cylinder 26a and piston 26 and normally operates to bias the latter downwardly'to swing the arm 25 to zero position as shown in Fig. 6. The arm 25 is connected through 7 .a lead 28 to one side of a suitable electrically operated gage 29 having a scale 29a graduated ment of the arm for the gage I8. 30 indicates a panel associated with the gage 29 and mounting a series of lamps 3|, one lamp for each ballast tank, one sided the lamps being grounded at 31a. The other sides of the lamps 3| are connected by leads 32 (one for each lamp) to contacts 32a, respe'ctivel'y, mounted on'an annular collar 33 (see Fig. '3) formed of insulating material and suitably fixed to the inner end of the valve casing 8a. The outer end of the shank Ib for the valve element I8 is provided with an arm 330, connected by a lead 34 with the battery 24, the arm being suitably insulated from the shank we The outer end of the arm 33a is arranged to engage the contacts 32a when the valve element It is rotated. The arm- 33a. is fixed to the shank. I 0b in alinement with the duct I5 and the contacts 32a are alined with the ports 8, respectively, whereby operation of the wheel Illa to supply air pressure to each of the pipes I will insure closing ofthe circuit for the lamp corresponding to the tank in which each pipe is mounted. In operation, assuming that the depth of tank 4 is to be determined, the valve element III is turned counter-clockwise, as viewed in Fig. 4 (clockwise as viewed in Fig. 6) from neutral -;"position until duct I5 registers with the port 8 related to. pipe Ia, which is connected to pipe I .of ballast tank 4; in this movement of the valve element II), the arm 33a sweeps over the contacts relatedto the lamps corresponding to tanks I,

2, and '3, momentarily lighting these lamps and comes to rest on the contact related to the lamp corresponding to tank 4, which lamp remains lighted while the depth of tank 4 is determined and notifies the officer in the pilot house which tank is being tested, whereas the gage 29 exhibits in lineal dimensions the static-head in pipe I of the tank, whereby the depth of water in the latter can be determined as already set forth.

The operating device Illa is preferably provided with an arrow 35 in alined relation to the duct I5.- The arrow 35 serves as a guide for the operative to indicate the position of the duct I5 when thedevice lflais being operated.

It will be observed that in setting the valves I32, as already set forth, they were adjusted in relation to the pressure due to resistance to air flow in the pipes Ia under the atmospheric (humidity) or barometrical conditions existing at that time. Where a change in these conditions takes place, the resistance to air flow in the pipes Ia is increased or decreased, so that -it is necessary, at the time any depth readings are to be made, to determine the air pressure required to overcome the resistance in the pipes Ia to air flow, and deduct the lineal measurement corresponding to this pressure from that indicated by the gage I8 for each depth reading, whereby the latter may be accurately determined." To avoid the time and labor required to re-set the valves I50, I provide auxiliary means,

indicated as an entirety at 36, for determining from time to time the approximate pressure measurement to overcome the resistance to air flow' in the pipes Ia, so that such measurement (instead of the initial dimension noted) may be noted and deducted from that indicated by the gage I8, as already set forth.- The means 36 consist of a pipe 31 extending through one of the space E, its outer end preferably terminating in one of the intermediate tanks at one side of the holds B. I The inner end of the pipe 31 is connected to a port 31b formed in the valve casing 8a in line with the ports 8, whereby thevalve element I9 of the valve 9 may be rotated to connect the conduit 14 with the'pipe 31 and supply air tothe latter. 370 indicates a valve provided in the pipe 31a adjacentto the valve 9, the valve 3'Ic'be'ingadjusted at the time the valves Ia: werewadjusted to regulate the air flow therethrough corresponding to that of the pipe Ia re- ;lated'to the most remote tank I or I. As shown,

same size as the pipes Ia and their valveslx.

9 respectively, to insure a correct reading in relation to the initial reading hereinbefore set forth.

The pipe 31 is open at its outer end and of sufllcient length so that when a test reading thereof .is made, the pressure shown by the gage 18 will approximate the resistance for all of the pipes 1a. The pipe 31 preferably terminates adjacent one of the intermediate ballast tanks so that the indicated resistance will approximate that of the pipes Ia related to those tanks more remote from and closer to the valve '9. When the valve. element is rotatedto connect the conduit 14 with the port 37b, the arm 33a engages a contact 37d, closing the circuit through the gage 29 and through a lead 38, which is connected to a lamp 38a,grounded at 3 la,jwhereby the pressure due to air flow resistance inthe pipe 3'! is exhibited at the station in the pilot house and such pressure reading is indicated by the lighting of the lamp 38a. 7

To those skilled in the art to which my invention relates many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. My disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

' What is claimed is:

1. In a system for determining at an operating station the liquid levels in the ballast tanks of a ship consisting of a plurality of pipes each depending vertically in oneof the ballast tanks to a position adjacent the bottom thereof, each said pipe terminating lwithan unobstructed open end to permit the rise and'iall therein of the liquid in the adjacent tank, a unitary rotary valve mechanism at the operating station provided with an inlet port anda plurality of outlet ports, one corresponding to each of the ballast tanks, a source of supply for a gaseous medium under a pressure, a conduit connecting said source of gaseous medium supply to the inlet port of said 7 valve mechanism, a separate pipe between each of said outlet ports of said valve mechanism and the upper end of one of said vertically disposed depending pipes, the plurality of pipes comprising respectively connectedseparate and depending pipes, including some substantially difierent in combined length, the rotatable vvalve element of said valve mechanism being operable to selectively establish communication between said conduit and each of said separate pipes to permit -fiovw of the gaseous medium therethrough to the adjacent vertically disposed depending pipe, the

supply of the gaseous medium to each said depending pipe serving to displace all of the liquid therein, adjustable flow restricting means in each separate pipe for initially equalizing the frictional resistance to flow through said separate and depending pipes, and a gage connected with said conduit for indicating the applied pressure for displacing the liquid from each depending pipe.

2. An apparatus as claimed in claim 1 wherein is provided a regulating valve between said source of gaseous medium supply and said gage for controlling the pressure of the gaseous medium in the system and a pressure relief valve is provided in said conduit between said regulating valve and said valve mechanism.

3. In a system for determining the liquid levels in a row of ballast tanks of a ship at an operating station located adjacent one end of said row, consisting of a source of supply for a gaseous medium under pressure, a rotary valve mechanism at the operating station and provided with an inlet port and a plurality of outlet ports, one for each tank, a conduit connecting said source of gaseous medium supply to the inlet port of said valve mechanism, a plurality of pipes connected at their inner ends to said outlet ports, respectively, each pipe consisting of a main section and a terminating dis-charge section, each of said discharge sections depending vertically through the top wall of one of said tanks and terminating with an unobstructed open end at a level adjacent the bottom thereof, the rotatable element of said valve mechanism being operable to selectively establish communication between said conduit and each of said pipes to permit flow of the gaseous medium therethrough to the adjacent depending pipe discharge section, the supply of the gaseous medium to each said depending pipe discharge section serving to displace all of the liquid therein, adjustable flow restricting means in each of said pipes adjacent said valve mechanism for initially equalizing the frictional resistance to flow therethrough, and a gage in said conduit for indicating the applied pressure for displacing the liquid from each of said depending pipe discharge sections.

JOSEPH N. MATTHEWS.

REFERENCES CITED The following references are of record in the file of this patent:

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